In recent years, as a technique for enlarging coverage of a wireless communication system, relay communication has been attracting attention (e.g., see Patent Literatures 1 and 2 below). In the relay communication, a relay station is disposed between two communication devices for which there is difficulty in directly transmitting and receiving wireless signals with good quality, and the wireless signals are relayed by the relay station. For example, in Long Term Evolution (LTE)-Advanced (hereinafter, referred to as an LTE-A) which is the next-generation cellular communication standard being planned by the Third Generation Partnership Project (3GPP), it is proposed that the throughput at a cell edge be enhanced using the relay communication of the relay station.
The relay communication in LTE-A is classified into two kinds known as type 1 and type 2. Type 1 is relay communication of the relay station to which the cell ID is allocated. The relay station of type 1 is treated as a base station in terms of a terminal device. On the other hand, type 2 is relay communication corresponding to operations of a repeater in wired communication by virtue of the relay station to which the cell ID is not allocated. The presence of the relay station of type 2 is typically not recognized by the terminal device.
The relay station playing a leading role in the relay communication may move by itself in a similar way to the mobile station. In particular, the fourth-generation (4G) cellular wireless communication mode represented by LTE-A is expected to have acceptable moving speeds of the mobile station and the relay station of up to 500 km/h. As a situation in which the movable relay station is used, for example, a situation in which the relay station is disposed in a train or a ship is considered. In this case, passengers and crews of the train or the ship use the mobile stations (e.g., terminals devices such as mobile PCs or smart phones) to carry out the wireless communication via the corresponding relay station.